“The end of the world will be along shortly,” a friend of mine remarked, after noticing what he thought was an erroneous whom in the hallowed pages of The New Yorker. But the example he pointed me to was an interesting one. It does not by any means imply that we are nearing the end times, though pedants may think otherwise by the time I’m done. The sentence occurred in a book review by Nathan Heller (November 19, 2012, Page 86):
|||But what about Sir Isaac Newton, whom some contend was autistic?|
Shouldn’t that whom, thought my friend, be who instead?
To answer the question, we have to be precise about the relevant rule. We’re never very sure of ourselves when it comes to whom. Style plays a role: Who are you supposed to trust? is normal style in Standard English, while Whom are you supposed to trust? is almost excessively formal. Purists call the former “a grammatical error” (as when I risked using normal style here on Lingua Franca), but it isn’t; you’d have to have a tin ear for language and a blind eye for literature to think that.
What is true, though, is that whom cannot be the subject of a tensed clause: *Whom broke this? is ungrammatical in all styles. Did Nathan Heller slip up?
It is worth taking a careful look at what Strunk & White’s The Elements of Style say about this kind of case (fourth edition, p. 11; the passage I refer to is in fact all due to White). Elements asserts that  is an error, and the whom should be corrected to who:
|||Virgil Soames is the candidate whom we think will win.|
But it also directly asserts that this is the relevant rule:
|||Strunk & White’s rule for the case of who in subordinate clauses:|
|When who introduces a subordinate clause, its case depends on its function in that clause.|
Take a second look at example . The clause that whom introduces is the relative clause modifying candidate, and the body of the clause reads we think will win. The main verb of that clause is think, and the subject is the pronoun we.
So whom is not the subject of the relative clause that it introduces in . It should therefore take the accusative form that all nonsubjects take. Thus by rule , whom is arguably correct. (That was not the intention. As usual, the grammatical pontifications in Elements are not based on an accurate grasp of syntax.)
Of course, although whom in  is not understood as the subject of the clause it introduces (the think clause), it is understood as a subject: the subject of will win. Had Elements been written by more competent authorities, the rule might have been phrased more like :
|||Alternate version of Strunk & White’s rule:|
|When who introduces a relative or interrogative clause, its case depends on its function in whatever clause it is functionally associated with.|
This has different consequences: It entails that the nominative form who is required whenever the word is understood as the subject of any tensed clause. By rule , Heller’s  does indeed have an incorrect whom (which may indeed mean the end of the world is nigh).
So which rule is the correct one? I feel sure you are expecting me to tell you (since the end of the world may depend on it). And you are probably not going to be happy when I do.
Merriam-Webster’s Dictionary of English Usage (1994), the finest English usage guide, citing Otto Jespersen (Modern English Grammar, vol. 3), notes that Shakespeare followed rule , the whom-favoring rule that purists don’t like. A few examples:
|||a.||Young Ferdinand, whom they suppose is drown’d… (“The Tempest”)|
|b.||Arthur, whom they say is kill’d to-night (“King John”)|
|c.||my wife … whom I thank heaven is an honest woman (“Measure for Measure”)|
Other data cited in support of rule  includes a sentence by Bennett Cerf and another from the 5 July 1971 issue of the The New York Times.
However, Henry Fielding and Charles Dickens are cited as following rule  instead, thus favoring who. And James Boswell and Benjamin Franklin seem to have vacillated between the two rules.
This raises the one thing that the nitpicking grammar Nazis hate most: diversity. Variation within Standard English. There seems to be no agreed unitary rule governing the inflection of who where it functions as subject of a clause to which it is not adjacent.
And why should there be? Nobody ordained or guaranteed that English would be uniquely fixed at all points. I’m sorry if you wanted it to be otherwise, but no Dark Lord has dominion over English grammar, with one rule to ring them all, and in the darkness bind them.